Discovery could lead to smaller batteries with more power and run time

Nanotechnology may one day usher in a
new era for electronics and other products with smaller portable
devices that run longer than the electronics we use today. Much
research is being conducted on carbon nanotubes (CNTs) for a myriad
of uses including electronics and batteries.

Battery research
is being conducted in several different areas. Researchers at MIT are
using viruses
to create batteries that can hold more power and run for longer
periods. Battery research is a hot bed of activity because the
batteries can be used in automobiles to help reduce pollution and our
need for oil. Improvements in battery technology will also lead to
smaller computers and mobile phones that offer more run time with
each charge.

One of the hallmarks of carbon nanotubes is that
fact that the CNTs are just about perfect according to researchers. A
professor and a graduate student at UC San Diego have discovered that
by introducing purposeful defects into CNT structures the defective
CNTs work better for the development of super capacitors.

Professor
Prabhakar Bandaru said, "While batteries have large storage
capacity, they take a long time to charge; while electrostatic
capacitors can charge quickly but typically have limited capacity.
However, super capacitors electrochemical capacitors incorporate the
advantages of both."

Bandaru is working with graduate
student Mark Hoefer on the research program studying CNTs. The pair
discovered that introducing
purposeful defects into the CNT structure created additional
charge sites and enhanced the charge storage properties of the
CNT.

Hoefer said, "We first realized that defective CNTs
could be used for energy storage when we were investigating their use
as electrodes for chemical sensors. During our initial tests we
noticed that we were able to create charged defects that could be
used to increase CNT charge storage capabilities."

The
researchers also found that other methods could increase or decrease
the charge capacity of the CNTs with defects such as bombarding them
with argon or hydrogen.

Bandaru said, "It is important to
control this process carefully as too many defects can deteriorate
the electrical conductivity, which is the reason for the use of CNTs
in the first place. Good conductivity helps in efficient charge
transport and increases the power density of these devices."

The
interesting part of this research is that one of the things that
first drew scientists and researchers to study CNTs was the fact that
the CNTs are nominally considered to be perfect structurally. In this
instance, the CNTs are better when they have a certain amount of
defects.

The two researchers think that their discovery could
lead to electronics that charge faster and last longer than what we
have today. Bandaru understands that much more research is required
on the subject and hopes that more researchers and engineers will
investigate the discovery.

Hoefer said, "We hope that our
research will spark future interest in utilizing CNTs as electrodes
in charge storage devices with greater energy and power densities."

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